FS in Thai massage shops is very much dependant on the girl and discretion, but I agree, it is rare and subject to trust, how often you visit the same girl and even then isn't always offered. If you want FS, you go elsewhere that provides that service.
I've been fortunate to have been offered it by a couple of girls in the last several years but trust me, it took many visits and often empty wallets to get that offered 😁
Ill health has put a stop to my punting days for now sadly.
I've been to DB many times but never been offered FS. I have a degree of scepticism about reviews claiming they have had FS there.